This talk focuses on the ways in which cross-border integration is studied by the discipline of (human) geography, to serve as an invitation for cross-fertilisation across different disciplines. It engages with the vibrant geographical debate on cross-border regionalisation, situating this debate within theoretical perspectives such as new regionalism, the rescaling of economic coordination and state power, the strategic selectivity of the state, and multi-scalar governance. It also compares existing empirical scenarios of cross-border integration across different contexts in the world. This talk, although formulated mainly at a theoretical and conceptual level, aims to provide analytical insights into future study of the Greater Bay Area, as well as the social, cultural and political implications of this initiative.